Separation of lead from solutions



summon 07mm non commons This invention relates to the separation of leadfrom solutions containing high concentrations of a soluble chloride e.g. from the ferrous chloride solutions obtained by treating with hdrochloric acid the mainly soluble residue erived from iron pyritesbyheating in the absence of air, or by treating iron pyrites with chlorinegas.

the treatment of themainly soluble f o residue of iron pyrites withhydrochloric acid, I obtain concentrated solutlonsof ferrous chloridecontaining ractically the whole of the lead present in t e originalmineral. The normal solubilityof lead chloride in water at ordinarytemperature, C. corresponds to about 6.8 gr. of lead per litre. By theprocesses described in the specifications of my applications Serial Nos.259,317 and 257,095, filed respectively March 5, 1928,

and February'25, 1928. obtain amounts of lead in the solutions as highas 15 gr. r

litre. It is impossible to separate lead from these solutions byordinary chemical methods; metallic iron does not cause separationdirectly, nor is any precipitate obtained with sulphuric acid orhydrogen sulphide.

In accordance with the present invention, displace the lead electr-chemically from o ferrous chloride solution by means of 30, metalliciron.

According to one method of efiecting this electro-chemical displacement,I subject the solution to electrolysis, emplo g a very low voltage only,one half to one v It being sufiicient. The cathode is a metal plate, onwhich the lead is deposited in a spon condition.

he spongy lead is removed periodically and compressed to free it fromadherent solution.

e anode may be of carbon or other inert 4o material, and may be immersedin a solution of sodium, calcium, magnesium or other similar chloridecontained in a which case chloride is evolved and may be liquefied orconverted into bleaching powder is etc.,i11 own manner. The anode may,how

ever, be an iron plate, in which case a qu'antity of iron, equivalent tothe lead deposited and to the small amount of hydrogen formed at thecathode, is taken into the solution.

0 The lead may be sold directly as crude metal,

porous vessel, in i and in Great-Britain Zl'ebmry 10, 1888.

or melted up and refined in the usual way. e recovery of lead is veryhigh, and amounts to 80-90% of that present in the original pyrites.

may also affect the separation of the lead electro-chemically by meansof an. iron copper couple, prepared by leaving iron filin s in contactwith a solution of copper sulp ate or a few moments. The filings afterwashmg are shaken with the iron lead chloride solution at a temperaturesomewhat above the normal; any temperature up to the boiling point mabejemployed, but 60 is suitable. Uiidcr-these conditions, the lead isdeposited by the electrochemical action oi the couple, the equivalentquantity of iron going into the solution. The ings used is chosen assomew at more than that theoretically r uired. When the action iscomplete, the lea associated with the excesspf iron, and the smallquantity of co per present in the couple, is removed by iii "tration; orotherwise, washed, pressed and re ed by any suitable method.

The methods of separating lead from solutions described may be a pliedalso to other solutions of lead qhlori e containing high concentrationsof a soluble chloride, e. g. to solutions of lead chloride in saturatedcommon salt solutions, such as are obtained in ,the leaching oflead-containing materials with hot brine solutions, whether neutral orcontaining hydrochloric acid.

,The lead is depositedin a spongy form if thei solution is kept cold,and the E. M. F. an hot solutions and higher E. M; F. and currentdensity, when I obtain the lead in acoherent sheet :Eorm.

I claim f e treatment 0 comprises treating such soluble residues withhydrochloric acid, thereby obtaining a chloride solution containing sucha high concentration of ferrouschloride as to inhibit the ordinaryreactions of lead in solution, and displacing the lead electrochemicallyfrom' the solution by means of metallic iron. c

uantity of fil- 2. The method of recoverin lead from soluble residuesobtained from t .treatment of yrites which comprises treating such sol-I by obtaining a chloride solution contaimn such a bi h concentration offerrous chlOri e as to inhibit the ordinary reactions of lead insolution, and causin iron to displace the lead electrochemicall y passin.a current between iron electr es immerse in the solution, using an E.MLF. less than that required to decom se ferrous chloride.

.3. The metho of recoverin lead from luble residues obtained from t etreatment 16 of yrites which comprises treating such solub e residueswith hydrochloric acid, there- 'by obtaining a chloride solutioncontaining such a hi h concentration or ferrous chloride as to inhiiitthe ordinary reactions of lead in so solution and displacing the leadelectrochemica y by passing a current between an iron anode and a metalcathode immersed in the solution to (fiposit lead on the cathode andusing an E. F. less than that required '25 to decompose the ferrouschloride.

4. The method of recovering lead from 901- uble residues obtained fromthe treatment of yrites which comgrises treating such so ub e residueswith by rochloric acid, thereb $0 obtaining a chloride solutioncontaining sue a higfiil concentration of ferrous Cl1101'1d6 as to in'bit the ordinary reactions of lead in solution, and displacing the leadelectrochemically by passin a current between iron 86 electrodesimmersed in the solution, kee;in%

the solution cold and using an E. M. 0 not more than about one volt.

5. The method of recoverin lead from soluble residues obtained from t etreatment of 40 pyrites which comprises treating such solu le residueswith hydrochloric acid, thereb; obtaining a chloride solution containingan a high concentration of ferrous chloride as to inhibit the ordinaryreactions of lead in solution and displacing the lead electrochemica yby passm a current between iron electrodes immersed 1n the solution,keeping the solution hot and using a high current densit and an E. M. F.insuflicient to decompose t e ferrous chloride.

6. The method of recovering1 lead from soluble residues obtained from te treatment of pyrites which comprises treating such soluble residueswith hydrochloric acid, thereby obtaining a chloride solution containingsuch a high concentration of ferrous chloride as to inhibit the ordinaryreactions of lead in solution, and, displacing; the leadelectrochemically by the action 0 a couple of so which one element isiron.

'- In testimony whereof I have signed my name. Y STANLEY ISAAC LEVY.

